1) If everything is setup correctly, do I have to go to each machine andstart Zookeeper server in each of them individually?2) I was thinking if I start it on one master machine (well there's noreal master) then all zookeepers in the quorum would be started, but thisis not how it works correct?3) If I start individually, then I get messages saying the otherzookeepers haven't started. Is that just a warning?4) When all of them are started, would they all be able to talk to eachother?

>Hello,>>Trying to follow directions from here:>http://zookeeper.apache.org/doc/trunk/zookeeperAdmin.html#sc_zkMulitServer>Setup>>to setup a cluster of zookeepers.>>Questions:>>1) If everything is setup correctly, do I have to go to each machine and>start Zookeeper server in each of them individually?>2) I was thinking if I start it on one master machine (well there's no>real master) then all zookeepers in the quorum would be started, but this>is not how it works correct?>3) If I start individually, then I get messages saying the other>zookeepers haven't started. Is that just a warning?>4) When all of them are started, would they all be able to talk to each>other?>>Sorry for the dumb questions and thanks for the help.

Thanks Jordan. Will definitely look at the cluster management tool. Inthe mean time, am I correct with my assumption in #4? Once all of them arestarted they would automagically start talking to each other, right?On Tue, May 8, 2012 at 2:36 PM, Jordan Zimmerman <[EMAIL PROTECTED]>wrote:

> Yes, you must start them all individually. ZooKeeper does not currently> have any cluster-wide management tools built in.>> FYI - we've open sourced a cluster management tool for ZooKeeper. Please> have a look:>> https://github.com/Netflix/exhibitor>> On 5/8/12 2:31 PM, "Something Something" <[EMAIL PROTECTED]> wrote:>> >Hello,> >> >Trying to follow directions from here:> >> http://zookeeper.apache.org/doc/trunk/zookeeperAdmin.html#sc_zkMulitServer> >Setup> >> >to setup a cluster of zookeepers.> >> >Questions:> >> >1) If everything is setup correctly, do I have to go to each machine and> >start Zookeeper server in each of them individually?> >2) I was thinking if I start it on one master machine (well there's no> >real master) then all zookeepers in the quorum would be started, but this> >is not how it works correct?> >3) If I start individually, then I get messages saying the other> >zookeepers haven't started. Is that just a warning?> >4) When all of them are started, would they all be able to talk to each> >other?> >> >Sorry for the dumb questions and thanks for the help.>>

Yes - they should. Keep in mind that the zoo.cfg, and the ID file must becorrect and in agreement on each instance. You can do a stat on eachinstance to see what state it's in:

>telnet localhost 2181 stat

-JZ

On 5/8/12 2:43 PM, "Something Something" <[EMAIL PROTECTED]> wrote:

>Thanks Jordan. Will definitely look at the cluster management tool. In>the mean time, am I correct with my assumption in #4? Once all of them>are>started they would automagically start talking to each other, right?>>>On Tue, May 8, 2012 at 2:36 PM, Jordan Zimmerman><[EMAIL PROTECTED]>wrote:>>> Yes, you must start them all individually. ZooKeeper does not currently>> have any cluster-wide management tools built in.>>>> FYI - we've open sourced a cluster management tool for ZooKeeper. Please>> have a look:>>>> https://github.com/Netflix/exhibitor>>>> On 5/8/12 2:31 PM, "Something Something" <[EMAIL PROTECTED]>>>wrote:>>>> >Hello,>> >>> >Trying to follow directions from here:>> >>> >>http://zookeeper.apache.org/doc/trunk/zookeeperAdmin.html#sc_zkMulitServe>>r>> >Setup>> >>> >to setup a cluster of zookeepers.>> >>> >Questions:>> >>> >1) If everything is setup correctly, do I have to go to each machine>>and>> >start Zookeeper server in each of them individually?>> >2) I was thinking if I start it on one master machine (well there's no>> >real master) then all zookeepers in the quorum would be started, but>>this>> >is not how it works correct?>> >3) If I start individually, then I get messages saying the other>> >zookeepers haven't started. Is that just a warning?>> >4) When all of them are started, would they all be able to talk to>>each>> >other?>> >>> >Sorry for the dumb questions and thanks for the help.>>>>

> Yes - they should. Keep in mind that the zoo.cfg, and the ID file must be> correct and in agreement on each instance. You can do a stat on each> instance to see what state it's in:>> >telnet localhost 2181> stat>> -JZ>> On 5/8/12 2:43 PM, "Something Something" <[EMAIL PROTECTED]> wrote:>> >Thanks Jordan. Will definitely look at the cluster management tool. In> >the mean time, am I correct with my assumption in #4? Once all of them> >are> >started they would automagically start talking to each other, right?> >> >> >On Tue, May 8, 2012 at 2:36 PM, Jordan Zimmerman> ><[EMAIL PROTECTED]>wrote:> >> >> Yes, you must start them all individually. ZooKeeper does not currently> >> have any cluster-wide management tools built in.> >>> >> FYI - we've open sourced a cluster management tool for ZooKeeper. Please> >> have a look:> >>> >> https://github.com/Netflix/exhibitor> >>> >> On 5/8/12 2:31 PM, "Something Something" <[EMAIL PROTECTED]>> >>wrote:> >>> >> >Hello,> >> >> >> >Trying to follow directions from here:> >> >> >>> >>> http://zookeeper.apache.org/doc/trunk/zookeeperAdmin.html#sc_zkMulitServe> >>r> >> >Setup> >> >> >> >to setup a cluster of zookeepers.> >> >> >> >Questions:> >> >> >> >1) If everything is setup correctly, do I have to go to each machine> >>and> >> >start Zookeeper server in each of them individually?> >> >2) I was thinking if I start it on one master machine (well there's no> >> >real master) then all zookeepers in the quorum would be started, but> >>this> >> >is not how it works correct?> >> >3) If I start individually, then I get messages saying the other> >> >zookeepers haven't started. Is that just a warning?> >> >4) When all of them are started, would they all be able to talk to> >>each> >> >other?> >> >> >> >Sorry for the dumb questions and thanks for the help.> >>> >>>>

I believe the "Node" field in the stat is the number of ZKNodes, notinstances in the ensemble. That stat looks good. It means that thatinstance is serving requests as a "follower" instance (one of theinstances will be the leader).

-JZ

On 5/8/12 2:54 PM, "Something Something" <[EMAIL PROTECTED]> wrote:

>Hmm...>>>Trying 127.0.0.1...>Connected to localhost.>Escape character is '^]'.>stat>Zookeeper version: 3.3.4-cdh3u3--1, built on 01/26/2012 20:09 GMT>Clients:> /127.0.0.1:42510[0](queued=0,recved=1,sent=0)>>Latency min/avg/max: 0/0/0>Received: 4>Sent: 3>Outstanding: 0>Zxid: 0x100000000>Mode: follower>Node count: 11>Connection closed by foreign host.>>>Not sure I understand this output. I have 9 nodes in the ensemble.>>On Tue, May 8, 2012 at 2:45 PM, Jordan Zimmerman><[EMAIL PROTECTED]>wrote:>>> Yes - they should. Keep in mind that the zoo.cfg, and the ID file must>>be>> correct and in agreement on each instance. You can do a stat on each>> instance to see what state it's in:>>>> >telnet localhost 2181>> stat>>>> -JZ>>>> On 5/8/12 2:43 PM, "Something Something" <[EMAIL PROTECTED]>>>wrote:>>>> >Thanks Jordan. Will definitely look at the cluster management tool.>>In>> >the mean time, am I correct with my assumption in #4? Once all of them>> >are>> >started they would automagically start talking to each other, right?>> >>> >>> >On Tue, May 8, 2012 at 2:36 PM, Jordan Zimmerman>> ><[EMAIL PROTECTED]>wrote:>> >>> >> Yes, you must start them all individually. ZooKeeper does not>>currently>> >> have any cluster-wide management tools built in.>> >>>> >> FYI - we've open sourced a cluster management tool for ZooKeeper.>>Please>> >> have a look:>> >>>> >> https://github.com/Netflix/exhibitor>> >>>> >> On 5/8/12 2:31 PM, "Something Something" <[EMAIL PROTECTED]>>> >>wrote:>> >>>> >> >Hello,>> >> >>> >> >Trying to follow directions from here:>> >> >>> >>>> >>>> >>http://zookeeper.apache.org/doc/trunk/zookeeperAdmin.html#sc_zkMulitServe>> >>r>> >> >Setup>> >> >>> >> >to setup a cluster of zookeepers.>> >> >>> >> >Questions:>> >> >>> >> >1) If everything is setup correctly, do I have to go to each>>machine>> >>and>> >> >start Zookeeper server in each of them individually?>> >> >2) I was thinking if I start it on one master machine (well>>there's no>> >> >real master) then all zookeepers in the quorum would be started, but>> >>this>> >> >is not how it works correct?>> >> >3) If I start individually, then I get messages saying the other>> >> >zookeepers haven't started. Is that just a warning?>> >> >4) When all of them are started, would they all be able to talk to>> >>each>> >> >other?>> >> >>> >> >Sorry for the dumb questions and thanks for the help.>> >>>> >>>>>>

We have a cluster of 17 machines. Somewhere in the HBase documentation Iread - usually we should divide by 2 & use an odd number. May be Imis-read. That's why I started Zookeeper on 9 machines. I guess, I don'tunderstand the difference between Nodes & Instance. I expected ZKNodes tobe 9. Please explain. Thanks a lot for your help.

On Tue, May 8, 2012 at 3:46 PM, Something Something<[EMAIL PROTECTED]> wrote:> Thanks. Took your advice & cut down the number to 5 instances. Confirmed> that one of them is a leader & the rest are followers. Now on to> installing HBase. Thanks again.

FWIW I typically recommend 3 or 5. 3 is fine, but 5 allows you to domaintenance (take a server out of production) and still be able tohandle an unexpected failure w/o the service going down.

On Wed, May 9, 2012 at 8:33 AM, Adam Rosien <[EMAIL PROTECTED]> wrote:> I have often gotten confused by the "Node Count" field from stat, thinking> it meant cluster nodes, not znodes. I have to remind myself every time I> see it. Folks amenable to changing the name?

The names are overloaded which is unfortunate, node vs znode vs servernode vs server instance.... Unfortunately it would be hard to changeat this point given many third party tools depend on the name. Perhaps4.0?